JP7664133B2 - Binder resin composition for toner - Google Patents

Description

The present invention relates to a binder resin composition for toners used for developing latent images formed in, for example, electrophotography, electrostatic recording, electrostatic printing, etc., and to a toner for developing electrostatic images containing the binder resin composition.

Patent Document 1 discloses a method for producing a toner containing crystalline polyester resin A and crystalline polyester resin B as resin materials, each having a melting point of 50°C to 120°C, which includes a step of producing crystalline polyester resin A by crystallizing the polyester resin capable of forming a crystalline structure by making crystalline polyester resin B coexist in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of a polyester resin capable of forming a crystalline structure, and (i) condensing and polymerizing a dicarboxylic acid component containing at least one compound selected from the group consisting of 4,4-biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and derivatives thereof, and a diol component containing at least one compound selected from the group consisting of 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and derivatives thereof, and (ii) having a melting point of 120°C to 250°C.

Patent document 2 discloses an electrophotographic toner that uses, as the main component of the binder resin, a polyester resin obtained from polyvalent carboxylic acids containing 2 to 80 mol % of a polyvalent carboxylic acid having a diphenyl skeleton and an aliphatic polyvalent alcohol and/or an alicyclic polyvalent alcohol.

JP 2016-50959 A Japanese Patent Application Publication No. 6-242631

In recent years, with the increase in the use of printers for industrial printing applications, there is an increasing demand for toners that provide excellent abrasion resistance to printed matter.
Conventionally, as a means for improving abrasion resistance, there has been a method of increasing the molecular weight of a resin to increase the strength of a coating film, but this is still not sufficient.

The present invention relates to a binder resin composition for toners that has excellent abrasion resistance for printed matter and a toner for developing electrostatic images that contains the binder resin composition.

The present invention relates to
[1] Formula (I):

(In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and/or a propylene group, x and y are the average number of moles of alkylene oxide added, each of which is a positive number, and the sum of x and y is 1 or more and 16 or less.)
and a carboxylic acid component containing at least one of a biphenyldicarboxylic acid compound and a dicarboxydiphenyl ether compound.
Regarding.

The toner binder resin composition of the present invention provides excellent abrasion resistance to printed matter.

The toner binder resin composition of the present invention contains an amorphous polyester resin which is a polycondensation product of an alcohol component containing an alkylene oxide adduct of bisphenol A and a carboxylic acid component containing at least one of a biphenyl dicarboxylic acid compound and a dicarboxy diphenyl ether compound. Although the details are unclear, it is presumed that the effect of the present invention is achieved by the interaction between aromatic rings of the raw monomers of the amorphous polyester resin. That is, since the amorphous polyester resin uses an alkylene oxide adduct of bisphenol A as the alcohol component and a biphenyl carboxylic acid compound or a dicarboxy diphenyl ether compound as the carboxylic acid component, the molecular structure has many aromatic rings, so that it has high rigidity, and the π-π interaction between the aromatic rings is expressed. When used as a binder resin, it is presumed that the strong plastic deformation when the toner layer is rubbed during printing can be suppressed, and the rub resistance of the printed matter is improved.

The alkylene oxide adduct of bisphenol A has the formula (I):

(In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and/or a propylene group, x and y are the average number of moles of alkylene oxide added, each of which is a positive number, and the sum of x and y is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less.)
Examples of the compound include an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A.

The content of the alkylene oxide adduct of bisphenol A represented by formula (I) in the alcohol component is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 100 mol%.

Other alcohol components include aliphatic diols, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, trimethylolpropane, and other trihydric or higher alcohols.

Examples of biphenyl carboxylic acid compounds include 2,2'-biphenyl dicarboxylic acid, 3,3'-biphenyl dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, and derivatives thereof. Examples of derivatives of biphenyl carboxylic acid include those in which the aromatic ring has 1 to 4 alkyl groups each having 1 to 4 carbon atoms, and alkyl esters of biphenyl carboxylic acid in which the alkyl group has 1 to 3 carbon atoms. In the present invention, the biphenyl carboxylic acid compound is preferably unsubstituted biphenyl carboxylic acid, and more preferably 2,2'-biphenyl dicarboxylic acid.

Examples of dicarboxydiphenyl ether compounds include 2,2'-dicarboxydiphenyl ether, 3,3'-dicarboxydiphenyl ether, 4,4'-dicarboxydiphenyl ether, and derivatives thereof. Examples of derivatives of dicarboxydiphenyl ether include those in which the aromatic ring has 1 to 4 alkyl groups each having 1 to 4 carbon atoms, and alkyl esters of dicarboxydiphenyl ether in which the alkyl group has 1 to 3 carbon atoms. In the present invention, the dicarboxydiphenyl ether compound is preferably an unsubstituted dicarboxydiphenyl ether, and more preferably 4,4'-dicarboxydiphenyl ether.

The carboxylic acid component contains at least one of a biphenyldicarboxylic acid compound and a dicarboxydiphenyl ether compound, but from the viewpoint of abrasion resistance, it is preferable that the carboxylic acid component contains a biphenyldicarboxylic acid compound.

The content of biphenyldicarboxylic acid compounds or dicarboxydiphenyl ether compounds, or the total content of biphenyldicarboxylic acid compounds and dicarboxydiphenyl ether compounds, in the carboxylic acid component, is preferably 15 mol% or more, more preferably 25 mol% or more, even more preferably 30 mol% or more, and is preferably 55 mol% or less, more preferably 45 mol% or less, even more preferably 42 mol% or less.

From the viewpoint of heat resistance storage stability, it is preferable that the carboxylic acid component further contains an aromatic dicarboxylic acid compound.

Examples of aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms, and among these, terephthalic acid is preferred.

The content of the aromatic dicarboxylic acid compound, preferably the content of terephthalic acid, in the carboxylic acid component is preferably 45 mol% or more, more preferably 55 mol% or more, even more preferably 60 mol% or more, and preferably 85 mol% or less, more preferably 75 mol% or less, even more preferably 70 mol% or less.

Other carboxylic acid components include aliphatic dicarboxylic acid compounds, trivalent or higher carboxylic acid compounds, etc.

In addition, the alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound, as appropriate, from the viewpoint of adjusting the molecular weight and softening point of the polyester resin.

From the viewpoint of adjusting the softening point of the polyester resin, the equivalent ratio of the carboxylic acid component to the alcohol component (COOH group/OH group) is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.75 or more, and is preferably 1.2 or less, more preferably 1.15 or less.

Amorphous polyester resins can be produced, for example, by polycondensing the raw material monomers, an alcohol component and a carboxylic acid component, in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and, if necessary, in the presence of an esterification promoter, a polymerization inhibitor, etc., at a temperature of preferably 160°C or higher, more preferably 200°C or higher, and preferably 250°C or lower, more preferably 240°C or lower.

Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamine, and tin compounds are preferred. The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, and more preferably 1 part by mass or less, relative to 100 parts by mass of the raw material monomer. Examples of the esterification promoter include gallic acid, etc. The amount of the esterification promoter used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, and more preferably 0.1 parts by mass or less, relative to 100 parts by mass of the raw material monomer. Examples of the polymerization inhibitor include tert-butylcatechol, etc. The amount of the polymerization inhibitor used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, and more preferably 0.1 parts by mass or less, relative to 100 parts by mass of the raw material monomer.

From the viewpoint of heat-resistant storage stability, the softening point of the amorphous polyester resin is preferably 80°C or higher, more preferably 83°C or higher, and even more preferably 90°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 120°C or lower, more preferably 110°C or lower, and even more preferably 100°C or lower.

The crystallinity of a resin is represented by a crystallinity index defined as the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, i.e., the value of [softening point/maximum endothermic peak temperature]. A crystalline resin is a resin having a crystallinity index of 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less.
On the other hand, an amorphous resin is a resin in which no endothermic peak is observed, or if an endothermic peak is observed, the crystallinity index is greater than 1.4, preferably greater than 1.5, more preferably 1.6 or more, or less than 0.6, preferably 0.5 or less.
The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, and the production conditions (e.g., reaction temperature, reaction time, cooling rate), etc. The maximum endothermic peak temperature refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In the case of a crystalline resin, the maximum endothermic peak temperature is the melting point.

From the viewpoint of heat-resistant storage stability, the glass transition temperature of the amorphous polyester resin is preferably 45°C or higher, more preferably 50°C or higher, and even more preferably 52°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 65°C or lower, more preferably 60°C or lower, and even more preferably 57°C or lower.

From the viewpoint of electrostatic charge stability, the acid value of the amorphous polyester resin is preferably 2 mgKOH/g or more, more preferably 4 mgKOH/g or more, and is preferably 20 mgKOH/g or less, more preferably 15 mgKOH/g or less.

From the viewpoint of electrostatic charge stability, the hydroxyl value of the amorphous polyester resin is preferably 10 mgKOH/g or more, more preferably 20 mgKOH/g or more, and is preferably 80 mgKOH/g or less, more preferably 65 mgKOH/g or less.

The weight average molecular weight of the amorphous polyester resin is preferably 2000 or more, more preferably 3000 or more, and even more preferably 4000 or more, from the viewpoint of heat-resistant storage stability, and is preferably 10000 or less, more preferably 8000 or less, and even more preferably 6500 or less, from the viewpoint of low-temperature fixability.

In the present invention, the polyester resin may be a polyester resin that has been modified to such an extent that its properties are not substantially impaired. Examples of modified polyester resins include polyester resins that have been grafted or blocked with phenol, urethane, epoxy, or the like, using the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like.

From the viewpoint of hot offset resistance, it is preferable that the toner binder resin composition of the present invention further contains an amorphous polyester resin (hereinafter also referred to as amorphous polyester resin AH) having a higher softening point than the amorphous polyester resin.

The difference in softening point between amorphous polyester resin AH and the amorphous polyester resin (hereinafter also referred to as amorphous polyester resin AL) is preferably 20°C or more, more preferably 30°C or more, even more preferably 38°C or more, and is preferably 60°C or less, more preferably 55°C or less, even more preferably 45°C or less.

The amorphous polyester resin AH is preferably a polycondensation product of an alcohol component containing an alkylene oxide adduct of bisphenol A represented by the above formula (I) and a carboxylic acid component containing an aromatic dicarboxylic acid compound.

The content of the alkylene oxide adduct of bisphenol A represented by formula (I) in the alcohol component is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 100 mol%.

Examples of aromatic dicarboxylic acid compounds include the same compounds as above, but terephthalic acid is preferred.

The content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 30 mol% or more, more preferably 35 mol% or more, even more preferably 40 mol% or more, and preferably 60 mol% or less, more preferably 55 mol% or less, even more preferably 50 mol% or less.

Examples of carboxylic acid components other than aromatic dicarboxylic acid compounds include aliphatic dicarboxylic acid compounds and trivalent or higher carboxylic acid compounds.

Examples of aliphatic dicarboxylic acid compounds include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid which may be substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, adipic acid, and anhydrides of these acids, and alkyl esters in which the alkyl group has 1 to 3 carbon atoms.

The content of the aliphatic dicarboxylic acid compound in the carboxylic acid component is preferably 20 mol% or more, more preferably 25 mol% or more, even more preferably 30 mol% or more, and preferably 50 mol% or less, more preferably 45 mol% or less, even more preferably 40 mol% or less.

Examples of trivalent or higher carboxylic acid compounds include trimellitic acid, pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

From the viewpoint of increasing the softening point, the content of the trivalent or higher carboxylic acid compound in the carboxylic acid component is preferably 3 mol% or more, more preferably 5 mol% or more, and even more preferably 8 mol% or more, and is preferably 35 mol% or less, more preferably 25 mol% or less.

In addition, the alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound, as appropriate, from the viewpoint of adjusting the molecular weight and softening point of the polyester resin.

From the viewpoint of adjusting the softening point of the polyester resin, the equivalent ratio of the carboxylic acid component to the alcohol component (COOH group/OH group) is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.75 or more, and is preferably 1.2 or less, more preferably 1.15 or less.

Amorphous polyester resin AH can be produced by polycondensation of an alcohol component and a carboxylic acid component in the same manner as amorphous polyester resin AL.

The softening point of the amorphous polyester resin AH is preferably 120°C or higher, more preferably 125°C or higher, and even more preferably 130°C or higher, from the viewpoint of hot offset resistance, and is preferably 160°C or lower, more preferably 150°C or lower, and even more preferably 145°C or lower, from the viewpoint of low-temperature fixability.

The glass transition temperature of the amorphous polyester resin AH is preferably 45°C or higher, more preferably 50°C or higher, and even more preferably 53°C or higher, from the viewpoint of heat resistance storage stability, and is preferably 70°C or lower, more preferably 65°C or lower, and even more preferably 60°C or lower, from the viewpoint of low-temperature fixability.

From the viewpoint of electrostatic charge stability, the acid value of the amorphous polyester resin AH is preferably 5 mgKOH/g or more, more preferably 10 mgKOH/g or more, and is preferably 40 mgKOH/g or less, more preferably 30 mgKOH/g or less.

From the viewpoint of electrostatic charge stability, the hydroxyl value of the amorphous polyester resin AH is preferably 5 mgKOH/g or more, more preferably 10 mgKOH/g or more, and is preferably 40 mgKOH/g or less, more preferably 30 mgKOH/g or less.

The weight average molecular weight of the amorphous polyester resin AH is preferably 50,000 or more, more preferably 70,000 or more, and even more preferably 100,000 or more, from the viewpoint of hot offset resistance, and is preferably 200,000 or less, more preferably 170,000 or less, and even more preferably 150,000 or less, from the viewpoint of low-temperature fixability.

The mass ratio of amorphous polyester resin AL to amorphous polyester resin AH (amorphous polyester resin AL/amorphous polyester resin AH) is preferably 30/70 or more, more preferably 40/60 or more, even more preferably 50/50 or more, and is preferably 90/10 or less, more preferably 85/15 or less, even more preferably 80/20 or less.

The total content of the amorphous polyester resin in the binder resin composition is preferably 80% by mass or more, more preferably 85% by mass or more, and preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 92% by mass or less.

From the viewpoint of low-temperature fixing property, it is preferable that the toner binder resin composition of the present invention further contains a crystalline polyester resin which is a polycondensation product of an alcohol component containing an aliphatic diol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound.

From the viewpoint of compatibility with the amorphous composite resin, it is preferable that the alcohol component of the crystalline polyester resin contains an aliphatic diol.

Examples of aliphatic diols include 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol.

The carbon number of the aliphatic diol is preferably 6 or more, and preferably 12 or less, more preferably 10 or less, from the viewpoint of adequate compatibility with the amorphous polyester resin.

In addition, from the viewpoint of improving the low-temperature fixing property of the toner, the aliphatic diol preferably has a hydroxyl group at the end of the carbon chain, and is more preferably an α,ω-linear alkanediol.

The alcohol component may contain alcohols other than aliphatic diols, but the content of aliphatic diols in the alcohol component is preferably 70 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 100 mol%.

Examples of alcohol components other than aliphatic diols include aromatic diols such as alkylene oxide adducts of bisphenol A, and trihydric or higher alcohols such as glycerin.

The carboxylic acid component of the crystalline polyester resin preferably contains an aliphatic dicarboxylic acid compound.

Examples of aliphatic dicarboxylic acid compounds include succinic acid (carbon number: 4), suberic acid (carbon number: 8), azelaic acid (carbon number: 9), sebacic acid (carbon number: 10), dodecanoic diacid (carbon number: 12), tetradecanoic diacid (carbon number: 14), succinic acid having an alkyl or alkenyl group on the side chain, anhydrides of these acids, and alkyl esters having 1 to 3 carbon atoms. In the present invention, carboxylic acid compounds include not only free acids, but also anhydrides that decompose during the reaction to generate acids, and alkyl esters having 1 to 3 carbon atoms. However, the number of carbon atoms of the alkyl group of the alkyl ester portion is not included in the number of carbon atoms of the aliphatic dicarboxylic acid compound.

The chain hydrocarbon group in the aliphatic dicarboxylic acid compound may be linear or branched, and the number of carbon atoms in the aliphatic dicarboxylic acid compound is preferably 4 or more, more preferably 6 or more, and even more preferably 10 or more, from the viewpoint of adequate compatibility with the amorphous polyester resin, and is preferably 14 or less, and more preferably 13 or less.

The content of the aliphatic dicarboxylic acid compound is preferably 70 moles or more, more preferably 80 moles or more, and preferably 100 moles or less, more preferably 96 moles or less, per 100 moles of the alcohol component.

The carboxylic acid component may contain carboxylic acid compounds other than aliphatic dicarboxylic acid compounds, but the content of the aliphatic dicarboxylic acid compounds in the carboxylic acid component is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 75 mol% or more, and preferably 98 mol% or less, more preferably 95 mol% or less, even more preferably 92 mol% or less.

From the viewpoint of low-temperature fixability, it is preferable that the carboxylic acid component further contains an aliphatic monocarboxylic acid compound.

Aliphatic monocarboxylic acid compounds include stearic acid, capric acid, lauric acid, myristic acid, palmitic acid, arachidic acid, behenic acid, lignoceric acid, etc., of which lauric acid is preferred.

The carbon number of the aliphatic monocarboxylic acid compound is preferably 8 or more, more preferably 10 or more, even more preferably 12 or more, and is preferably 30 or less, more preferably 24 or less, even more preferably 20 or less.

The content of the aliphatic monocarboxylic acid compound in the carboxylic acid component is preferably 2 mol% or more, more preferably 5 mol% or more, and preferably 40 mol% or less, more preferably 30 mol% or less.

Other carboxylic acid compounds include aromatic dicarboxylic acid compounds such as terephthalic acid and isophthalic acid, and trivalent or higher carboxylic acid compounds such as trimellitic acid and pyromellitic acid.

Crystalline polyester resins can be produced by polycondensing alcohols and carboxylic acid compounds in the same manner as amorphous polyester resins. The reaction temperature for polycondensation is preferably 120°C or higher, more preferably 180°C or higher, and preferably 230°C or lower, more preferably 220°C or lower.

From the viewpoint of storage stability, the softening point of the crystalline polyester resin is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 100°C or lower, and more preferably 90°C or lower.

From the viewpoint of storage stability, the melting point of the crystalline polyester resin is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 100°C or lower, and more preferably 90°C or lower.

From the viewpoint of electrostatic charge stability, the acid value of the crystalline polyester resin is preferably 2 mgKOH/g or more, more preferably 5 mgKOH/g or more, and is preferably 30 mgKOH/g or less, more preferably 20 mgKOH/g or less.

From the viewpoint of electrostatic charge stability, the hydroxyl value of the crystalline polyester resin is preferably 1 mgKOH/g or more, more preferably 2 mgKOH/g or more, and is preferably 50 mgKOH/g or less, more preferably 40 mgKOH/g or less.

The weight average molecular weight of the crystalline polyester resin is preferably 4,000 or more, more preferably 6,000 or more, and even more preferably 8,000 or more, from the viewpoint of heat-resistant storage stability, and is preferably 30,000 or less, more preferably 25,000 or less, and even more preferably 20,000 or less, from the viewpoint of low-temperature fixability.

The content of the crystalline polyester resin in the binder resin composition is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 8% by mass or more, and is preferably 20% by mass or less, and more preferably 15% by mass or less.

The mass ratio of the crystalline polyester resin to the amorphous polyester resin (crystalline polyester resin/amorphous polyester resin) is preferably 2/98 or more, more preferably 5/95 or more, and even more preferably 8/92 or more, from the viewpoint of abrasion resistance and image density, and is preferably 20/80 or less, and more preferably 15/85 or less, from the viewpoint of charging stability.

The binder resin composition may contain resins other than the amorphous polyester resin and the crystalline polyester resin to the extent that the effects of the present invention are not impaired. Examples of other resins include polyester resins other than the amorphous polyester resin and the crystalline polyester resin described above, vinyl resins such as styrene-acrylic resin, epoxy resin, polycarbonate, polyurethane, and composite resins containing two or more of these resins.

The total content of the amorphous polyester resin and the crystalline polyester resin in the binder resin composition is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass.

Furthermore, the present invention provides a toner containing the binder resin composition for toner of the present invention as a binder resin, specifically, a toner for developing electrostatic images containing the binder resin composition for toner of the present invention and a colorant.

The content of the binder resin composition in the toner is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and preferably 99% by mass or less, more preferably 98% by mass or less, even more preferably 95% by mass or less.

As the colorant, dyes, pigments, magnetic materials, etc., which are used as colorants for toners, can be used. In the present invention, the toner may be either a black toner or a color toner.

As colorants, dyes, pigments, magnetic materials, etc. used as toner colorants can be used. Examples include carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment red 122, pigment green B, rhodamine B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, disazo yellow, etc. In the present invention, the toner may be either a black toner or a color toner.

From the viewpoint of improving the image density and low-temperature fixability of the toner, the content of the colorant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the binder resin composition.

The toner for developing electrostatic images of the present invention may contain additives such as a release agent, a charge control agent, a magnetic powder, a flowability improver, a conductivity adjuster, a reinforcing filler such as a fibrous substance, an antioxidant, and a cleaning property improver, in addition to the binder resin composition and colorant, and preferably contains a release agent and a charge control agent.

Examples of release agents include hydrocarbon waxes such as polypropylene wax, polyethylene wax, polypropylene-polyethylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and oxides thereof; ester waxes such as carnauba wax, montan wax, and deacidified waxes thereof, and fatty acid ester wax; fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts; and the like, which can be used alone or in combination of two or more.

The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, from the viewpoint of toner transferability, and is preferably 160°C or lower, more preferably 140°C or lower, even more preferably 120°C or lower, and even more preferably 110°C or lower, from the viewpoint of low-temperature fixability.

The content of the release agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, relative to 100 parts by mass of the binder resin composition, from the viewpoints of the low-temperature fixability and offset resistance of the toner and the dispersibility in the binder resin, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less.

The charge control agent is not particularly limited, and may contain either a positively charged charge control agent or a negatively charged charge control agent.

Positively charged charge control agents include nigrosine dyes such as "Nigrosine Base EX", "Oil Black BS", "Oil Black SO", "Bontron N-01", "Bontron N-04", "Bontron N-07", "Bontron N-09", and "Bontron N-11" (all manufactured by Orient Chemical Industries Co., Ltd.); triphenylmethane dyes containing a tertiary amine as a side chain; quaternary ammonium salt compounds such as "Bontron P-51" (manufactured by Orient Chemical Industries Co., Ltd.), cetyltrimethylammonium bromide, and "COPY CHARGE PX VP435 (Clariant), etc.; polyamine resins, such as AFP-B (Orient Chemical Industries, Ltd.); imidazole derivatives, such as PLZ-2001 and PLZ-8001 (both manufactured by Shikoku Chemical Industries, Ltd.); styrene-acrylic resins, such as FCA-701PT and FCA-201-PS (Fujikura Chemical Industries, Ltd.), etc.

Examples of negatively chargeable charge control agents include metal-containing azo dyes, such as "Varifast Black 3804", "Bontron S-31", "Bontron S-32", "Bontron S-34", and "Bontron S-36" (all manufactured by Orient Chemical Industry Co., Ltd.), "Aizen Spiron Black TRH", and "T-77" (manufactured by Hodogaya Chemical Co., Ltd.); metal compounds of benzilic acid compounds, such as "LR-147" and "LR-297" (both manufactured by Nippon Carlit Co., Ltd.); metal compounds of salicylic acid compounds, such as "Bontron E-81", "Bontron E-84", "Bontron E-88", and "Bontron E-304" (all manufactured by Orient Chemical Industry Co., Ltd.), and "TN-105" (manufactured by Hodogaya Chemical Co., Ltd.); copper phthalocyanine dyes; and quaternary ammonium salts, such as "COPY CHARGE NX VP434 (Clariant), nitroimidazole derivatives, etc.; organometallic compounds, etc.

From the viewpoint of the charge stability of the toner, the content of the charge control agent is preferably 0.01 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, relative to 100 parts by mass of the binder resin composition.

The toner of the present invention may be obtained by any of the conventionally known methods such as the melt kneading method, the emulsion phase inversion method, and the polymerization method, but from the viewpoint of productivity and dispersibility of the colorant, a pulverized toner by the melt kneading method is preferred. In the case of a pulverized toner by the melt kneading method, for example, the binder resin (binder resin composition), the colorant, and, if necessary, the raw materials such as a release agent and a charge control agent are uniformly mixed in a mixer such as a Henschel mixer, and then melt kneaded in an internal kneader, a single-screw or twin-screw extruder, an open roll type kneader, etc., and cooled, pulverized, and classified to produce the toner.

In the production of toner, if the binder resin composition is made of multiple resins, a binder resin composition in which multiple resins are mixed in advance may be used, but when producing the toner, each resin may be directly used for mixing the raw materials.

In order to improve the transferability of the toner of the present invention, it is preferable to use an external additive. Examples of external additives include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as resin particles such as melamine-based resin fine particles and polytetrafluoroethylene resin fine particles, and two or more types may be used in combination. Of these, silica is preferred, and from the viewpoint of the transferability of the toner, hydrophobic silica that has been hydrophobized is more preferred.

Hydrophobic treatment agents for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octyltriethoxysilane (OTES), methyltriethoxysilane, etc.

From the viewpoint of the chargeability, fluidity, and transferability of the toner, the average particle size of the external additive is preferably 10 nm or more, more preferably 15 nm or more, and is preferably 250 nm or less, more preferably 200 nm or less, and even more preferably 90 nm or less.

From the viewpoint of the chargeability, fluidity, and transferability of the toner, the content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.3 parts by mass or more, per 100 parts by mass of the toner particles before treatment with the external additive, and is preferably 5 parts by mass or less, and more preferably 3 parts by mass or less.

The volume median particle diameter ( _D50 ) of the toner of the present invention is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. In this specification, the volume median particle diameter ( _D50 ) means a particle diameter at which the cumulative volume frequency calculated by volume fraction is 50% calculated from the smallest particle diameter. In addition, when the toner is treated with an external additive, the volume median particle diameter of the toner particles before treatment with the external additive is regarded as the volume median particle diameter of the toner.

The toner of the present invention can be used as it is as a single-component developing toner, or mixed with a carrier as a two-component developing toner, in image forming devices using either a single-component developing method or a two-component developing method.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The physical properties of the resins and the like can be measured by the following methods.

[Softening point of resin]
Using a flow tester "CFT-500D" (Shimadzu Corporation), 1g of sample is heated at a temperature increase rate of 6℃/min while applying a load of 1.96MPa with the plunger, and extruding the sample from a nozzle with a diameter of 1mm and length of 1mm. The plunger descent distance of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[Maximum endothermic peak temperature of resin]
Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan, Inc.), 0.01 to 0.02 g of sample is weighed into an aluminum pan and cooled from room temperature (20°C) to 0°C at a rate of 10°C/min. The sample is then maintained at that temperature for 1 minute. The endothermic peak is then measured while increasing the temperature to 180°C at a rate of 10°C/min. The temperature of the endothermic peak with the largest peak area is regarded as the maximum endothermic peak temperature.

[Glass transition temperature of resin]
Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan, Inc.), 0.01 to 0.02 g of the sample is weighed into an aluminum pan, heated to 200°C, and cooled from that temperature to 0°C at a rate of 10°C/min. The sample is then heated at a rate of 10°C/min, and the glass transition temperature is determined as the temperature at the intersection of an extension of the baseline below the maximum endothermic peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the top of the peak.

[Acid value of resin]
Measurements are performed based on the method of JIS K 0070:1992, except that the measurement solvent is changed from the ethanol and ether mixture specified in JIS K 0070 to a mixture of acetone and toluene (acetone:toluene = 1:1 (volume ratio)) for amorphous resins and a mixture of chloroform and dimethylformamide (chloroform:dimethylformamide = 7:3 (volume ratio)) for crystalline resins.

[Hydroxyl value of resin]
Measure based on the method of JIS K 0070:1992, except that the measurement solvent is changed from the ethanol and ether mixture specified in JIS K 0070 to tetrahydrofuran.

[Weight average molecular weight of resin]
The weight average molecular weight is determined by gel permeation chromatography (GPC) according to the following method.
(1) Preparation of sample solution: Dissolve the sample in tetrahydrofuran (amorphous resin) or chloroform (crystalline resin) at 40° C. to a concentration of 0.5 g/100 mL. Next, filter this solution using a PTFE-type membrane filter "DISMIC-25JP" (manufactured by Toyo Roshi Kaisha, Ltd.) with a pore size of 0.20 μm to remove insoluble components to obtain the sample solution.
(2) Molecular weight measurement Using the following measurement equipment and analytical column, tetrahydrofuran (amorphous resin) or chloroform (crystalline resin) is passed as the eluent at a flow rate of 1 mL per minute, and the column is stabilized in a thermostatic bath at 40°C. 100 μL of the sample solution is injected into the column and measurement is performed. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. The calibration curve used here was prepared using several types of monodisperse polystyrene (A-500 (5.0×10 ² ), A-1000 (1.01×10 ³ ), A-2500 (2.63×10 3 ), A-5000 (5.97×10 ³ ), F-1 (1.02×10 ⁴ ), F-2 (1.81× ^{10 4 )} , F-4 (3.97×10 ⁴ ), F-10 (9.64×10 ⁴ ), F-20 (1.90×10 ⁵ ), F-40 (4.27×10 ⁵ ), F-80 (7.06×10 ⁵ ), F-128 (1.09×10 ⁶ ) manufactured by Tosoh Corporation) as standard samples. The numbers in parentheses indicate molecular weights.
Measuring device: HLC-8220GPC (Tosoh Corporation)
Analytical column: TSKgel GMH _XL + TSKgel G3000H _XL (manufactured by Tosoh Corporation)

[Melting point of release agent]
Using a differential scanning calorimeter "DSC 210" (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample is weighed into an aluminum pan, heated to 200°C at a heating rate of 10°C/min, and cooled from that temperature to -10°C at a heating rate of 5°C/min. Next, the sample is heated to 180°C at a heating rate of 10°C/min and measured. The maximum endothermic peak temperature observed from the obtained melting endothermic curve is regarded as the melting point of the release agent.

[Average particle size of external additives]
The average particle size refers to the number-average particle size, and is calculated by measuring the particle sizes (average of major and minor axes) of 500 particles in a scanning electron microscope (SEM) photograph and averaging these by number.

[Volume Median Particle Size of Toner]
Measuring device: Coulter Multisizer II (manufactured by Beckman Coulter, Inc.)
Aperture diameter: 50μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter, Inc.)
Electrolyte: Isoton II (Beckman Coulter, Inc.)
Dispersion solution: Emulgen 109P (Kao Corporation, polyoxyethylene lauryl ether, HLB (Griffin): 13.6) was dissolved in the electrolyte to adjust the concentration to 5% by mass. Dispersion conditions: 10 mg of a measurement sample was added to 5 mL of the dispersion solution, and the mixture was dispersed for 1 minute using an ultrasonic disperser (machine name: US-1, manufactured by SND Corporation, output: 80 W). Thereafter, 25 mL of the electrolyte solution was added, and the mixture was further dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion solution.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte so as to reach a concentration at which the particle sizes of 30,000 particles can be measured in 20 seconds, and 30,000 particles are measured, and the volume median particle size (D ₅₀ ) is determined from the particle size distribution.

Resin Production Example 1
The raw material monomers other than 2,2'-biphenyldicarboxylic acid and the esterification catalyst shown in Table 1 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a fractionation column, a dehydration tube, a cooling tube, and a nitrogen inlet tube, and the temperature was raised to 235°C over 2 hours in a mantle heater in a nitrogen atmosphere. After confirming that the reaction rate reached 95% or more at 235°C, the mixture was cooled to 180°C. Then, 2,2'-biphenyldicarboxylic acid was added, and the temperature was raised to 220°C over 2 hours. After reacting at 220°C for 1 hour, the reaction was continued at 8 kPa until the desired softening point was reached, and amorphous polyester resins (resins AL1, AL3 to AL7) were obtained. The reaction rate in the present invention refers to the value of the amount of water produced by reaction (mol)/theoretical amount of water produced (mol) x 100.

Resin Production Example 2
The raw material monomers other than 4,4'-dicarboxydiphenyl ether and the esterification catalyst shown in Table 1 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a fractionation column, a dehydration tube, a cooling tube, and a nitrogen inlet tube, and the temperature was raised to 235°C over 2 hours in a mantle heater in a nitrogen atmosphere. After confirming that the reaction rate reached 95% or more at 235°C, the mixture was cooled to 180°C. Thereafter, 4,4'-dicarboxydiphenyl ether was added, and the mixture was heated to 220°C over 2 hours. After reacting at 220°C for 1 hour, the reaction was continued at 8 kPa until the desired softening point was reached, to obtain an amorphous polyester resin (resin AL2).

Resin Production Example 3
The raw material monomers and esterification catalyst other than 2,2'-biphenyldicarboxylic acid shown in Table 1 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a fractionation column, a dehydration tube, a cooling tube, and a nitrogen inlet tube, and the mixture was heated in a mantle heater in a nitrogen atmosphere at 180°C for 1 hour, then heated from 180°C to 230°C at a rate of 10°C/h, and polycondensed at 230°C for 10 hours. The mixture was further reacted at 230°C and 8.0 kPa for 1 hour, and then cooled to 180°C. Then, 2,2'-biphenyldicarboxylic acid was added, and the mixture was heated to 220°C over 2 hours. After reacting at 220°C for 1 hour, the mixture was reacted at 8 kPa until the desired softening point was reached, to obtain an amorphous polyester resin (resin AL8).

Resin Production Example 4
The raw material monomers and esterification catalyst shown in Table 1 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a fractionating column, a dehydration tube, a cooling tube, and a nitrogen inlet tube, and the flask was kept at 140° C. for 1 hour in a nitrogen atmosphere in a mantle heater, and then the temperature was increased from 140° C. to 200° C. at a rate of 10° C./h, and polycondensation reaction was carried out at 200° C. for 1 hour. The reaction was further carried out at 200° C. and 8.0 kPa until the desired softening point was reached, to obtain an amorphous polyester resin (Resin AL9).

Resin Production Example 5
The raw material monomers and esterification catalyst other than adipic acid and trimellitic anhydride shown in Table 2 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a fractionation column, a dehydration tube, a cooling tube, and a nitrogen inlet tube, and the temperature was raised to 235°C over 2 hours in a mantle heater in a nitrogen atmosphere. After confirming that the reaction rate reached 95% or more at 235°C, the mixture was cooled to 180°C. Adipic acid and trimellitic anhydride were then added, and the mixture was heated to 220°C over 2 hours. After reacting at 220°C for 1 hour, the reaction was continued at 8 kPa until the desired softening point was reached, to obtain an amorphous polyester resin (resin AH1).

Resin Production Example 6
The raw material monomers and esterification catalyst shown in Table 2 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a fractionating column, a dehydration tube, a cooling tube, and a nitrogen inlet tube, and the mixture was kept at 140° C. for 1 hour in a nitrogen atmosphere in a mantle heater, and then the temperature was increased from 140° C. to 200° C. at a rate of 10° C./h, and a polycondensation reaction was carried out at 200° C. for 1 hour. The reaction was further carried out at 200° C. and 8.0 kPa until the desired softening point was reached, to obtain a crystalline polyester resin (resin C1).

Examples 1 to 7 and Comparative Examples 1 and 2 (Example 7 is a reference example)
As the binder resin, 60 parts by mass of Resin AL, 30 parts by mass of Resin AH, and 10 parts by mass of Resin C shown in Table 3 were mixed thoroughly with 1 part by mass of a negative charge control agent "Bontron E-81" (manufactured by Orient Chemical Industry Co., Ltd.), 5 parts by mass of a colorant "Pigment blue 15:3" (manufactured by Dainichi Seika Chemicals Co., Ltd.), and 2 parts by mass of a release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 80°C) in a Henschel mixer, and then melt-kneaded at a roll rotation speed of 200 r/min and a heating temperature inside the roll of 100°C using a co-rotating twin-screw extruder with a kneading section total length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm. The mixture was fed at a rate of 20 kg/h and an average residence time of about 18 seconds. The resulting molten and kneaded product was cooled, coarsely pulverized, and then pulverized in a jet mill and classified to obtain toner particles having a volume median particle size (D ₅₀ ) of 8 μm.

1.0 part by mass of hydrophobic silica "AEROSIL NAX 50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: HMDS, average particle size: approximately 30 nm) was added as an external additive to 100 parts by mass of the obtained toner particles, and the mixture was mixed in a Henschel mixer to obtain a toner.

Test Example [Abrasion Resistance]
A solid image with a toner amount of 0.50 mg/ ^cm2 was fixed by passing it through a fixing device adjusted to 180°C as the evaluation paper. The fixed image was left for one month in an environment of 40°C and 80% relative humidity. The fixed image was rubbed five times back and forth with a sand eraser with a bottom surface of ¹⁵ mm x 7.5 mm and a load of 500 g, and the optical reflection density before and after rubbing was measured using a reflection densitometer "RD-915" (Macbeth Co., Ltd.), and the reduction rate (%) of the image density was calculated from (1-(reflection density after rubbing/reflection density before rubbing)) x 100 to evaluate the abrasion resistance of the fixed image. The results are shown in Table 3.

From the above results, it is apparent that all of Examples 1 to 7 have good abrasion resistance.
In contrast, Comparative Example 1, in which the alcohol component of the amorphous polyester resin is an aliphatic diol rather than an alkylene oxide adduct of bisphenol A, and Comparative Example 2, in which the carboxylic acid component does not contain either a biphenyldicarboxylic acid compound or a dicarboxydiphenyl ether compound, are found to lack abrasion resistance.

The toner for developing electrostatic images containing the binder resin composition for toner of the present invention is suitable for use in developing latent images formed in electrostatic image developing methods, electrostatic recording methods, electrostatic printing methods, etc.

Claims (7)

Formula (I):

(In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and/or a propylene group, x and y are the average number of moles of alkylene oxide added, each of which is a positive number, and the sum of x and y is 1 or more and 16 or less.)
and a carboxylic acid component containing terephthalic acid and at least one of a biphenyldicarboxylic acid compound and a dicarboxydiphenyl ether compound, wherein the biphenyldicarboxylic acid compound is 2,2'-biphenyldicarboxylic acid , the content of the biphenyldicarboxylic acid compound or the dicarboxydiphenyl ether compound, or the total content of the biphenyldicarboxylic acid compound and the dicarboxydiphenyl ether compound, in the carboxylic acid component, is 25 mol % or more and 55 mol % or less, and the content of the terephthalic acid in the carboxylic acid component is 45 mol % or more and 75 mol % or less. The binder resin composition for toner according to claim 1, wherein the glass transition temperature of the amorphous polyester resin is 45°C or higher and 65°C or lower. 3. The binder resin composition for toner according to claim 1 , wherein the dicarboxydiphenyl ether compound is 4,4'-dicarboxydiphenyl ether. 4. The binder resin composition for toner according to claim 1, wherein the content of the biphenyldicarboxylic acid compound or the dicarboxydiphenyl ether compound, or the total content of the biphenyldicarboxylic acid compound and the dicarboxydiphenyl ether compound, in the carboxylic acid component, is 25 mol % or more and 45 mol % or less. 5. The binder resin composition for toner according to claim 1 , wherein the content of terephthalic acid in the carboxylic acid component is 55 mol % or more and 75 mol % or less. The binder resin composition for toner according to any one of claims 1 to 5 , further comprising a crystalline polyester resin. 7. A toner for developing electrostatic images, comprising the binder resin composition for toners according to claim 1 and a colorant.